Stated first Ace printing, dated, with complete number line. Paperback Original per ISFDB. Tight, flat, square book with creased and cupped spine, edge and corner wear and toned pages. 

World War IV
The lucky ones died early...Ted Quantrill is a survivor. If that means bearing arms for the religious fanatics who make up the new government, he'll do it. If it means ruthlessly hunting down dissidents and "unacceptables", he'll do it. The time may come when he has the luxury of pondering what all this survival at any cost has done to him inside - but only if he's alive to take advantage of it...

Governments across the globe ducked for cover. Long-drilled and partly prepared, millions of RUS urbanites sealed themselves into subway tunnels, then slid blast-and-firestorm-proof hatches into place to ride out the blast-furnace interval. Most Americans were asleep, and in any case had only the sketchiest notion of adequate shelter. A few city dwellers—the smaller the city, the better their chances—sped beyond their suburbs before freeway arterials became clots of blood and machinery.
The American public had by turns ignored and ridiculed its Cassandras, who had all warned against our increasing tendency to crowd into our cities. We had always found some solution to our problems, often at the last minute. Firmly anchored in most Americans was the tacit certainty that, even to the problem of nuclear war against population centers, there must be a uniquely American solution; we would find it.

The solution was sudden death. A hundred million Americans found it.